Relic gull
| Relic gull | ||||||||||||
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Relic Gull ( Ichthyaetus relictus ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Ichthyaetus relictus | ||||||||||||
| ( Lönnberg , 1931) |
The relict gull ( Ichthyaetus relictus ), also known as the Lönnberg gull or Gobi black -headed gull , is a species of bird from the subfamily of gulls . It occurs in Kazakhstan , Russia , Mongolia and China . Wintering areas are known from South Korea . Until 1971 it was considered a subspecies of the black- headed gull ( Ichthyaetus melanocephalus ). The species was named by the Swedish zoologist Einar Lönnberg , who described the holotype collected in April 1929 by Karl Georg Söderbom in 1931 . The taxon was originally placed in the genus Larus , after a taxonomic revision of the gulls in 2005 (Pons et al. 2005), the International Ornithological Committee reclassified it to the genus Ichthyaetus .
features
The relict gull reaches a size of 44 to 45 centimeters. The sexes look the same. The head and almost the entire neck are black, except for a light brown area between the beak and eyes. A white spot can be seen above and below the dark red-brown eyes. The top is light gray. The rump is white. The wings are light gray with black subterminal bands on the longest wings. The underside and tail are white. In winter plumage the head is white or white with variable dark markings. Eye ring, beak and legs are dark red. The young birds have a white head with brown speckles. The tail has a dark band on them. The bill is dark brown at the beginning, with the base of the lower bill being lighter and later turning orange-red. The legs are dark gray. The eye ring is black.
distribution
Breeding colonies have been recorded for the following areas, among others: At Lake Alakol and Lake Balkhash in Kazakhstan , at Lake Barun-Torey, at Lake Zun-Torey, in Khotogor Bay and in Teli Bay in the Chita region in Transbaikalia, on the island of Fal'shivyi in the Primorye region , for the regions Khyargas Nuur, Khovd Khar Us Nuur National Park, Mönhö Hayrhan Uula, Bulgan Gol, Ihes Nuur, Ögiy Nuur, Hangayn Nuruu and Boon Tsagaan Nur in Mongolia as well as Jilin, Hulun Nur, Gaxun Nur, Shangdu, Wuchuan, Ulansuhai Nur, Hokhot, Baotou, Balaheai, Moren He, Boerjiang Nur, Hojia Nur, Dongsheng and Taolimiao-Alashan Nur in Inner Mongolia in China.
Non-breeding birds or winter guests migrate to Japan , South Korea and Vietnam .
habitat
The breeding colonies of the relict gull are located at altitudes below 1500 m in dry steppes as well as in sand dunes at salt lakes or slightly salty lakes with strongly fluctuating water levels. The relic gull makes strict demands on its habitat and for the successful establishment of breeding colonies it needs humid and warm weather conditions as well as huge areas.
Way of life
The relic gull nests in colonies, usually on small islands in large lakes. The breeding season extends from early May to early July. The clutch sizes vary between one to four eggs. The relic gull first breeds at the age of three. The diet consists of invertebrates, 90 percent of which make up mosquito larvae, small fish and vegetarian food. In Mongolia it occasionally hunts the Brandt steppe vole ( Lasiopodomys brandtii ).
Existence and endangerment
The relic gull was only known for a long time from the type specimen that was collected in 1929 on the lower course of the Edsin Gols in the western Gobi in the eastern part of Mongolia. In 1965, about 100 breeding pairs were rediscovered at Lake Zun Torey in Transbaikalia , Russia . In 1968 another 120 breeding pairs were observed at Lake Alakol in Kazakhstan .
The changes in the water level influence the breeding success and the loss of wetlands in arid regions in connection with climate change could seriously affect the stocks in the near future. Stalking and competition from other species of gulls, as well as hailstorms and floods, lead to high boy mortality and a reduction in breeding productivity.
Human disturbance has contributed to high chick mortality rates in Russia and China and has placed breeding colonies at particular risk from bad weather, reenactment and nest abandonment. Taolimiao-Alashan Nur, one of the main breeding colonies in China, is threatened by tourism projects.
BirdLife International classifies the relic gull in the "vulnerable" category and estimates the population of mature adult birds to be between 2,500 and 10,000 individuals with a total population of 12,000.
literature
- Warren B. King on the behalf of the International council for bird preservation (ICBP) and the Survival service commission of IUCN (1978-1979): Red Data Book 2: Aves (2nd edition). IUCN, Morges, Switzerland. ISBN 0-87474-583-7
- Johannes Erritzoe: The Birds of CITES and How to Identify Them. 1993
- Pons JM, Hassanin, A., Crochet PA (2005). Phylogenetic relationships within the Laridae (Charadriiformes: Aves) inferred from mitochondrial markers. Molecular phylogenetics and evolution 37 (3): 686-699